Field of the Invention
The present invention relates to an exposure apparatus, exposure method, and method of manufacturing an article.
Description of the Related Art
Upon manufacturing a semiconductor device, liquid crystal display device, or the like, an exposure apparatus including an illumination optical system which illuminates a reticle (mask) pattern with light, and a projection optical system which projects the reticle pattern onto a substrate is used.
In the exposure apparatus, after repetition of exposure processes, materials vaporized from a resist applied to a substrate and an outgas from components deposit (are absorbed) on surfaces of optical elements of the illumination optical system and projection optical system and react with exposure light, thus contaminating the surfaces of the optical elements (contamination). Thus, a technique for removing (cleaning) contaminants by irradiating the optical elements with infrared light or radiation is proposed by Japanese Patent Laid-Open No. 2002-270501.
However, since this related art requires a step of removing a material adhered on the surfaces of the optical elements in addition to a step of exposing a substrate to light, a down time is generated in the exposure apparatus, thus lowering the throughput. Also, when the optical elements are irradiated with infrared light, they absorb the infrared light, and their temperatures rise, thus causing thermal deformations of the optical elements.